Electromagnetic Protection Method for Live-Line Working Robots Based on Three-Level Collaborative Filtering and Shielding

Abstract

This invention discloses an electromagnetic protection method for live-line working robots based on three-level collaborative filtering and shielding, including: device-level protection: with the goal of ensuring power and signal integrity, filtering and layout optimization are performed on the printed circuit boards of each module of the robot; the filtering and layout optimization includes printed circuit board grounding and stack-up optimization, power network hierarchical filtering, and sensitive signal line filtering and isolation; module-level protection: each functional module in the robot is locally shielded and the interface signals between modules are filtered; whole-machine-level protection: the whole robot is shielded with a pre-set composite material shell; system-level filtering and transient protection are performed on all external cable ports; and an equipotential and grounding system is constructed.

Description

Technical Field

[0001] This invention relates to the field of electric robots, and in particular to an electromagnetic protection method for live-line working robots based on three-level collaborative filtering and shielding. Background Technology

[0002] Currently, the power industry is increasingly using live-line working robots for the inspection and maintenance of power transmission and transformation equipment to ensure personnel safety and improve power supply reliability. When operating at high potentials (such as 110kV and above), robots face extremely strong power frequency electromagnetic fields, transient overvoltages, and high-frequency broadband interference from arc discharge. This electromagnetic interference can couple to the robot's internal control system through conduction, induction, and radiation, causing core controller malfunctions, system crashes, sensor signal distortion, and communication interruptions, seriously threatening operational safety and success rates.

[0003] Existing protection solutions have the following limitations: First, they focus on macroscopic structural shielding (such as using an all-metal body or adding local shielding covers). While this can resist spatial radiation interference to some extent, it has limited effectiveness in suppressing interference conducted through power lines and signal lines, and significantly increases the robot's weight and inertia. Second, at the circuit design level, simple filtering is usually only performed at the power input, failing to build a deep protection system covering "device-module-system". There is a lack of systematic solutions for key issues such as common impedance coupling between digital and analog circuits and the propagation of high-frequency noise within the PCB board.

[0004] Therefore, a new technical solution is urgently needed to address the technical problem of how to achieve coordinated protection of the internal and external electromagnetic environments of a circuit board while simultaneously suppressing conducted interference and isolating radiated interference. Summary of the Invention

[0005] This invention provides an electromagnetic protection method for live-line working robots based on three-level coordinated filtering and shielding, which solves the technical problem of how to achieve coordinated protection of the internal and external electromagnetic environments of the circuit board while taking into account both conducted interference suppression and radiated interference isolation.

[0006] To achieve the above objectives, this invention provides an electromagnetic protection method for live-line working robots based on three-level cooperative filtering and shielding, comprising:

[0007] Device-level protection: With the goal of ensuring power and signal integrity, the printed circuit boards of each module of the robot are filtered and optimized in terms of layout. The filtering and layout optimization settings include printed circuit board grounding and stack-up optimization, power network hierarchical filtering, and sensitive signal line filtering and isolation.

[0008] Module-level protection: Local shielding and filtering of inter-module interface signals are performed on each functional module in the robot.

[0009] Whole-machine level protection: The robot is shielded with a pre-designed composite material shell; all external cable ports are filtered and protected against transients; and an equipotential and grounding system is constructed.

[0010] Preferably, printed circuit board grounding and stack-up optimization includes:

[0011] The printed circuit board is arranged from top to bottom as a first signal layer, a ground layer, a second signal layer, a power layer, a ground layer, and a third signal layer, with a preset isolation medium between each layer; the ground terminal of each filter capacitor in the printed circuit board is connected to the nearest ground layer through vias; the indentation distance between the physical boundary of the power layer and the physical boundary of the ground layer is greater than or equal to 20 times the thickness of the preset isolation medium.

[0012] Preferably, the power network hierarchical filtering includes:

[0013] In the printed circuit board, decoupling capacitor banks are deployed near each power supply pin; the decoupling capacitor bank consists of a preset large-capacity energy storage capacitor connected in parallel with a preset small-capacity high-frequency ceramic capacitor.

[0014] An input filter circuit consisting of an EMI filter is installed at the DC power input of each signal layer.

[0015] Preferably, the EMI filters installed at the DC power input of each signal layer are designed with individual parameters, including:

[0016] Measure the level of unfiltered interference noise on the robot within a preset time period; obtain the chip sensitivity threshold of the target signal layer; and obtain the required attenuation spectrum based on the interference noise level and the chip sensitivity threshold.

[0017] The filter order and cutoff frequency are determined based on the first formula for capacitors and inductors according to the topology of the selected EMI filter; the cutoff frequency is obtained according to the required attenuation spectrum and filter order; and the inductance and capacitance values ​​of the selected EMI filter are obtained according to the cutoff frequency, the first formula, and the impedance mismatch principle.

[0018] Preferably, the cutoff frequency is obtained based on the required attenuation spectrum and the filter order; the inductance and capacitance values ​​of the selected EMI filter are obtained based on the cutoff frequency, the first calculation formula, and the impedance mismatch principle, including:

[0019] The cutoff frequencies, obtained based on the required attenuation spectrum and filter order, include:

[0020] Ideally, the ideal insertion loss of an nth-order LC filter increases with frequency at a slope of 20ndB / dec. Therefore, by shifting a straight line with a slope of 20n tangent to the curve of the desired attenuation spectrum, the straight line becomes the ideal insertion loss asymptote of the filter. The intersection of the insertion loss asymptote and the horizontal axis is taken as the cutoff frequency of the nth-order LC filter.

[0021] Based on the cutoff frequency, the first calculation formula, and the impedance mismatch principle, the inductance and capacitance values ​​of the selected EMI filter are as follows:

[0022] By combining the cutoff frequency with the first calculation formula, the second calculation formula is obtained; the parameter values ​​of the first-order components of the filter are determined according to the impedance mismatch principle; the parameter values ​​of the remaining components are determined according to the second calculation formula and the parameter values ​​of the first-order components; wherein, the parameter values ​​of components of the same type are set to be equal.

[0023] Preferably, the filtering and isolation of sensitive signal lines includes:

[0024] For signal lines that transmit analog sampling signals, high-speed digital clock signals, and communication bus signals, a low-pass filter is formed by connecting a preset resistor in series and a capacitor to ground in parallel at the driving end or receiving end according to the frequency characteristics of the corresponding signal; or an interface chip with integrated filtering function is selected at the driving end or receiving end.

[0025] The digital, analog, and power circuits are partitioned, and differential traces are used on both sides of the sensitive signal lines; the center-to-center spacing of parallel signal traces is kept greater than 3 times the line width.

[0026] Preferably, the process of performing partial shielding and filtering of inter-module interface signals for each functional module in the robot includes:

[0027] Each functional module in the robot is locally shielded, with independent metal shielding cavities set up for the high-frequency noise source module and the high-sensitivity module. The metal shielding cavities are connected to the ground plane of the printed circuit board in the module with low impedance through multi-point or seam welding. The power lines and signal lines entering and leaving each functional module are filtered through feedthrough filters or filter networks. The filter network consists of onboard common-mode chokes and filter capacitors.

[0028] Preferably, shielding the entire robot with a pre-designed composite material shell includes:

[0029] The robot's main body shell is made of a composite structure of conductive plastic and metal mesh, and a nickel-zinc ferrite conductive coating for shielding broadband electromagnetic interference is sprayed on the inner wall or outer surface of the shell in preset key parts.

[0030] Preferably, system-level filtering and transient protection for all external cable ports includes:

[0031] All external connectors passing through the robot's main body housing are filtered connectors, or a centralized filter protection plate is installed behind the external connectors; the filter protection plate integrates common-mode filters, transient suppression diodes, and gas discharge tubes for power, communication, and control lines; when the shielding layer of any external cable enters the robot's main body housing, a metal cable gland with electromagnetic compatibility is used.

[0032] Preferably, constructing an equipotential and grounding system includes:

[0033] An equipotential bus is installed inside the robot's insulated bucket platform, and the grounding terminals of any metal shielding shell and filter in the robot are connected to the equipotential bus in a star topology.

[0034] The present invention has the following beneficial effects:

[0035] The present invention provides an electromagnetic protection method for live-line working robots based on three-level collaborative filtering and shielding. Based on three-level collaborative filtering and shielding, it organically combines circuit board-level filtering design with hierarchical system-level shielding to form a defense-in-depth system. It comprehensively addresses the interference from three aspects: the source of interference, the propagation path, and sensitive equipment. While controlling weight and cost, it can significantly improve the reliability and stability of the robot in extreme electromagnetic environments.

[0036] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0037] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0038] Figure 1 This is a schematic diagram of the electromagnetic protection framework for a live-line working robot based on a preferred embodiment of the present invention, featuring three-level collaborative filtering and shielding.

[0039] Figure 2 This is a schematic diagram of the printed circuit board stack-up according to a preferred embodiment of the present invention.

[0040] Figure 3 This is a schematic diagram of the ideal insertion loss asymptote of an nth-order LC filter according to a preferred embodiment of the present invention. Detailed Implementation

[0041] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0042] In a preferred embodiment of the present invention, a power line inspection robot for 500kV transmission lines is used as an example. This robot needs to cope with transient arc pulse interference with amplitudes up to 900A, energy concentrated within 100MHz, and a highest frequency component reaching 1.3GHz.

[0043] See Figure 1 In a preferred embodiment of the present invention, an electromagnetic protection method for live-line working robots based on three-level collaborative filtering and shielding is provided, comprising:

[0044] (1) Device-level protection: With the goal of ensuring power and signal integrity, the printed circuit boards of each module of the robot are filtered and the layout is optimized. The filtering and layout optimization settings include the grounding and stack-up optimization of the printed circuit board, the hierarchical filtering of the power network, and the filtering and isolation of sensitive signal lines.

[0045] In a preferred embodiment of the present invention, the optimization of printed circuit board grounding and stack-up includes:

[0046] See Figure 2 To suppress near-field radiation coupling of up to 5kV / m generated by arc discharge, the core control board adopts a six-layer design. The printed circuit board is arranged sequentially from top to bottom as the first signal layer, ground layer, second signal layer, power layer, ground layer, and third signal layer, with preset isolation media between each layer. Both ground layers are complete, uninterrupted ground planes, utilizing a dual-ground layer structure to provide a complete reference plane and reduce the inductance of the signal return path. The ground terminals of all filter capacitors in the printed circuit board are connected to the nearest ground layer via vias to provide a return path with minimal impedance. The indentation distance between the physical boundary of the power layer and the physical boundary of the ground layer is [not specified]. Thickness greater than or equal to 20 times the preset isolation medium ,include:

[0047] ;

[0048] In a preferred embodiment of the present invention, =0.1mm, set the indentation distance =2mm, effectively confining more than 70% of the edge magnetic flux inside the plate layer, preventing edge radiation effect.

[0049] In a preferred embodiment of the present invention, the power network hierarchical filtering includes:

[0050] In the printed circuit board, decoupling capacitor banks are deployed near each power supply pin of each important integrated circuit; the decoupling capacitor bank consists of a preset large-capacity energy storage capacitor connected in parallel with a preset small-capacity high-frequency ceramic capacitor.

[0051] An input filtering circuit consisting of an EMI filter is installed at the DC power input of each signal layer. Specifically, for the onboard power input (such as a 24V to 5V circuit), a board-level EMI filter is designed at the board-level DC power input to filter out conducted interference.

[0052] In a preferred embodiment of the present invention, the EMI filters installed at the DC power input of each signal layer are individually parameter-designed, including:

[0053] Measure the level of unfiltered interference noise on the robot within a preset time period. ; Obtain the chip sensitivity threshold of the target signal layer Based on the interference noise level and chip sensitivity threshold Obtain the desired attenuation spectrum :

[0054] ;

[0055] The filter order and cutoff frequency are determined based on the first formula for capacitors and inductors according to the topology of the selected EMI filter; the cutoff frequency is obtained according to the required attenuation spectrum and filter order; and the inductance and capacitance values ​​of the selected EMI filter are obtained according to the cutoff frequency, the first formula, and the impedance mismatch principle.

[0056] In a preferred embodiment of the present invention, the cutoff frequency is obtained based on the required attenuation spectrum and the filter order; the inductance and capacitance values ​​of the selected EMI filter are obtained based on the cutoff frequency, the first calculation formula, and the impedance mismatch principle, including:

[0057] The cutoff frequencies, obtained based on the required attenuation spectrum and filter order, include:

[0058] See Figure 3 Ideally, the ideal insertion loss of an nth-order LC filter increases with frequency at a slope of 20ndB / dec. Therefore, by shifting a straight line with a slope of 20n tangent to the curve of the desired attenuation spectrum (i.e., the insertion loss requirement in the figure), the straight line becomes the asymptote of the filter's ideal insertion loss. The intersection of the insertion loss asymptote and the horizontal axis is taken as... Cutoff frequency of an LC filter If the corner frequency is too low, the filter order can be increased. .

[0059] Based on the cutoff frequency, the first calculation formula, and the impedance mismatch principle, the inductance and capacitance values ​​of the selected EMI filter are as follows:

[0060] By combining the cutoff frequency with the first calculation formula, the second calculation formula is obtained; the first-order component parameter values ​​of the filter are determined according to the impedance mismatch principle; the remaining component parameter values ​​are determined according to the second calculation formula and the first-order component parameter values; among them, if the filter is multi-order, research shows that the filter insertion loss is the maximum when each inductor and capacitor parameter is equal. At this time, there are still only two unknown component parameters. Therefore, the parameter values ​​of components of the same type are set to be equal.

[0061] In a preferred embodiment of the present invention, considering the high-frequency characteristics of arc discharge, the capacitor is selected as an MLCC capacitor with extremely low equivalent series inductance, and the inductor is selected as a ferrite bead or power inductor with good high-frequency characteristics, and it is necessary to verify that it does not undergo magnetic saturation under peak current.

[0062] In a preferred embodiment of the present invention, the alternative EMI filters include LC type, T type, and The three types of typical EMI filters are shown in Table 1.

[0063] Table 1. First calculation formula for a typical EMI filter

[0064] ;

[0065] In a preferred embodiment of the present invention, the filtering and isolation of the sensitive signal line includes:

[0066] For signal lines that transmit analog sampling signals, high-speed digital clock signals, and communication bus signals, a low-pass filter is formed by connecting a preset resistor in series and a capacitor to ground in parallel at the driving end or receiving end according to the frequency characteristics of the corresponding signal; or an interface chip with integrated filtering function is selected at the driving end or receiving end.

[0067] In a preferred embodiment of the present invention, a low-pass filter is constructed on the CPU's reset (RESET), interrupt (IRQ), and other signal lines that are extremely sensitive to transient pulses, by connecting a resistor R (1KΩ) in series with the pin and a capacitor C (100pF) in parallel. (Time constant) This demonstrates that it can effectively filter out nanosecond-level arc burrs.

[0068] Digital, analog, and power circuits are partitioned, and differential traces are used on both sides of sensitive signal lines to suppress common-mode interference. The center-to-center spacing of parallel signal traces is maintained at more than three times the trace width to reduce crosstalk to below -30dB. The differential impedance of the CAN bus and high-speed differential signal lines is strictly controlled. To enhance common-mode suppression capability.

[0069] (2) Module-level protection: Local shielding and filtering of inter-module interface signals are performed on each functional module of the robot. Specifically, this includes:

[0070] Each functional module in the robot is locally shielded, with independent metal shielding cavities for high-frequency noise source modules and high-sensitivity modules. These metal shielding cavities are connected to the ground plane of the printed circuit board within the module using multi-point or seam welding methods with low impedance.

[0071] In a preferred embodiment of the invention, core units such as the motor driver and industrial computer are independently shielded. The shielding housing is made of 6061 aluminum alloy and milled as a whole, with a wall thickness of 3mm, to meet the comprehensive shielding requirements for the strong magnetic and electric fields generated by arc discharge (shielding effectiveness SE>70dB). Conductive rubber gaskets are installed at the gaps in the housing to ensure the continuity of conductivity at the joints, and all heat dissipation openings have a diameter of less than 10mm (corresponding to 1 / 20 of the wavelength of 1.3GHz) to prevent high-frequency electromagnetic wave leakage.

[0072] Power and signal lines entering and exiting each functional module are filtered through feedthrough filters or filter networks; the filter network consists of onboard common-mode chokes and filter capacitors.

[0073] In a preferred embodiment of the present invention, a dedicated interface filtering circuit is designed at the cable entry and exit ports of each module. Considering the high impedance (current source characteristic) of arc discharge interference sources at high frequencies, a capacitor-inductor-capacitor (CLC) circuit is adopted, following the impedance mismatch principle. Type topology:

[0074] Front-end capacitor: Connected in parallel on the interface side to provide a low-impedance bypass path for high-impedance interference sources.

[0075] Intermediate inductor: A high-permeability manganese-zinc ferrite (such as Z7K material) common-mode choke is selected to obtain a large common-mode impedance and attenuate low-frequency interference.

[0076] Back-end capacitor: Connected in parallel to the internal circuit side to filter out residual high-frequency noise.

[0077] Among them, the intermediate inductor is the common-mode inductor. The front-end capacitor and the back-end capacitor are the Y capacitors. It complies with safety regulations regarding leakage current limits.

[0078] (3) Overall protection: The robot is shielded with a pre-designed composite material shell; all external cable ports are filtered and protected against transients; and an equipotential and grounding system is constructed.

[0079] In a preferred embodiment of the present invention, shielding the entire robot with a pre-designed composite material shell includes:

[0080] The robot's main body shell is made of a composite structure of conductive plastic and metal mesh, and a nickel-zinc ferrite conductive coating for shielding broadband electromagnetic interference is sprayed on the inner wall or outer surface of the shell in preset key parts.

[0081] In a preferred embodiment of the present invention, all metal components, including the robot arm, metal base, and shielded chassis, are reliably connected by flexible copper braided strips with a cross-sectional area of ​​not less than 6 mm², ensuring that the DC contact resistance between the components is less than [value missing]. This prevents secondary discharge or ground potential backflash caused by uneven potential among components during the instant of potential transfer.

[0082] In a preferred embodiment of the invention, the outer shell is constructed using a carbon fiber composite material with an inner copper foil lining. The copper foil layer utilizes its high electrical conductivity to reflect and shield high-frequency electric fields. A nickel-zinc ferrite conductive coating is sprayed onto the surface of the copper foil layer or the inner wall of the chassis, utilizing its magnetic loss characteristics to absorb electromagnetic wave energy in the 30MHz~1GHz frequency band and suppress cavity resonance. Through the application of composite materials, effective shielding against broadband arc radiation fields is achieved while ensuring the robot's lightweight design.

[0083] In a preferred embodiment of the present invention, system-level filtering and transient protection for all external cable ports includes:

[0084] All external connectors passing through the robot's main body housing are filtered connectors, or a centralized filter protection plate is installed behind the external connectors. The filter protection plate integrates common-mode filters, transient suppression diodes, and gas discharge tubes for power, communication, and control lines. When the shielding layer of any external cable enters the robot's main body housing, a metal cable gland with electromagnetic compatibility is used to achieve a 360-degree surround overlap between the shielding layer and the housing wall, ensuring that high-frequency interference current is directly discharged through the housing and does not flow into the internal circuit. All external cables of the robot are shielded cables with a braiding density of not less than 64 braids.

[0085] In a preferred embodiment of the present invention, constructing an equipotential and grounding system includes:

[0086] An equipotential bus is installed inside the robot's insulated bucket platform. The grounding terminals of any metal shielding shell and filter in the robot are connected to the equipotential bus in a star topology to ensure internal potential balance and provide a controllable discharge path for interference current.

[0087] After completing the three-level collaborative protection design, verification was conducted. EMTP software was used to simulate and calculate the current waveform, and CST software was used to simulate and calculate the shielding effectiveness of the shielded enclosure and the cable coupling voltage. A high-voltage lifting platform was built in the shielded laboratory to simulate the process of a robot approaching a 500kV live conductor at different speeds, monitoring for any robot resetting, communication packet loss, or malfunctions. Specifically, this included:

[0088] Electromagnetic Simulation: A robot system model including detailed PCB layout, shielding cavity, and cable bundles was established using 3D full-wave electromagnetic simulation software (such as CST, ANSYS HFSS). The excitation source was set to a 500kV / m power frequency uniform field or a standard pulse interference waveform. The induced noise spectrum of key chip pins and signal lines was extracted through simulation to verify that it was below the chip's immunity threshold. Simultaneously, the insertion loss of the filter was simulated. Optimize its parameters.

[0089] Actual measurement verification: Operating voltage test: Under 500kV power frequency voltage, a high-precision oscilloscope and current probe were used to monitor the noise amplitude and waveform of each key test point (such as MCU power supply, ADC input, and communication bus) to confirm that it meets the design expectations.

[0090] Arc discharge assessment: In a simulated arcing experiment, a broadband near-field probe and a spectrum analyzer were used to capture the high-frequency radiation spectrum generated by the arc. The interference spectrum intensity measured at the internal sensitive circuits before and after the implementation of protective measures was compared to verify the suppression effect of system-level shielding and port filtering on broadband pulse interference. The final passing criterion was that the robot's functions remained uninterrupted and the communication bit error rate did not exceed the standard.

[0091] The present invention provides an electromagnetic protection method for live-line working robots based on three-level collaborative filtering and shielding. Based on three-level collaborative filtering and shielding, it organically combines circuit board-level filtering design with hierarchical system-level shielding to form a defense-in-depth system. It comprehensively addresses the interference from three aspects: the source of interference, the propagation path, and sensitive equipment. While controlling weight and cost, it can significantly improve the reliability and stability of the robot in extreme electromagnetic environments.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An electromagnetic protection method for live-line working robots based on three-level collaborative filtering and shielding, characterized in that, include: Device-level protection: With the goal of ensuring power and signal integrity, the printed circuit boards of each module of the robot are filtered and the layout is optimized. The filtering and layout optimization settings include printed circuit board grounding and stack-up optimization, power network hierarchical filtering, and sensitive signal line filtering and isolation. Module-level protection: Local shielding and filtering of inter-module interface signals are performed on each functional module in the robot. Whole-machine level protection: The entire robot is shielded using a pre-designed composite material shell; System-level filtering and transient protection are applied to all external cable ports; Construct an equipotential and grounding system; The power network hierarchical filtering includes: In the printed circuit board, decoupling capacitor banks are deployed near each power supply pin; the decoupling capacitor bank consists of a preset large-capacity energy storage capacitor connected in parallel with a preset small-capacity high-frequency ceramic capacitor. An input filter circuit consisting of an EMI filter is installed at the DC power input of each signal layer. The EMI filters installed at the DC power input of each signal layer are designed with individual parameters, including: Measure the level of unfiltered interference noise on the robot within a preset time period; obtain the chip sensitivity threshold of the target signal layer; and obtain the required attenuation spectrum based on the interference noise level and the chip sensitivity threshold. The filter order and cutoff frequency are determined based on the topology of the selected EMI filter using a first calculation formula with respect to capacitance and inductance. The cutoff frequency is obtained based on the required attenuation spectrum and the filter order. The inductance and capacitance values ​​of the selected EMI filter are obtained based on the cutoff frequency, the first calculation formula, and the impedance mismatch principle.

2. The electromagnetic protection method for live-line working robots based on three-level collaborative filtering and shielding according to claim 1, characterized in that, The printed circuit board grounding and stack-up optimization includes: The printed circuit board is arranged from top to bottom as a first signal layer, a ground layer, a second signal layer, a power layer, a ground layer, and a third signal layer, with a preset isolation medium between each layer; the ground terminal of each filter capacitor in the printed circuit board is connected to the nearest ground layer through vias; the indentation distance between the physical boundary of the power layer and the physical boundary of the ground layer is greater than or equal to 20 times the thickness of the preset isolation medium.

3. The electromagnetic protection method for live-line working robots based on three-level cooperative filtering and shielding according to claim 2, characterized in that, The cutoff frequency is obtained based on the required attenuation spectrum and the filter order, including: Ideally, the ideal insertion loss of an nth-order LC filter increases with frequency at a slope of 20ndB / dec. Therefore, by shifting a straight line with a slope of 20n tangent to the curve of the desired attenuation spectrum, the straight line becomes the ideal insertion loss asymptote of the filter. The intersection of the insertion loss asymptote and the horizontal axis is taken as the cutoff frequency of the nth-order LC filter. Based on the cutoff frequency and the first calculation formula combined with the impedance mismatch principle, the inductance and capacitance values ​​of the selected EMI filter are as follows: By combining the cutoff frequency with the first calculation formula, a second calculation formula is obtained; the parameter values ​​of the first-order components of the filter are determined according to the impedance mismatch principle; the parameter values ​​of the remaining components are determined according to the second calculation formula and the parameter values ​​of the first-order components; wherein, the parameter values ​​of components of the same type are set to be equal.

4. The electromagnetic protection method for live-line working robots based on three-level cooperative filtering and shielding according to claim 3, characterized in that, The filtering and isolation of the sensitive signal lines includes: For signal lines that transmit analog sampling signals, high-speed digital clock signals, and communication bus signals, a low-pass filter is formed by connecting a preset resistor in series and a capacitor to ground in parallel at the driving end or receiving end according to the frequency characteristics of the corresponding signal; or an interface chip with integrated filtering function is selected at the driving end or receiving end. The digital, analog, and power circuits are partitioned, and differential traces are used on both sides of the sensitive signal lines; the center-to-center spacing of parallel signal traces is kept greater than 3 times the line width.

5. The electromagnetic protection method for live-line working robots based on three-level cooperative filtering and shielding according to claim 4, characterized in that, The process of performing local shielding on each functional module of the robot and filtering of inter-module interface signals includes: Each functional module in the robot is locally shielded, with the high-frequency noise source module and the high-sensitivity module having independent metal shielding cavities. The metal shielding cavities are connected to the ground plane of the printed circuit board in the module with low impedance through multi-point or seam welding. The power lines and signal lines entering and leaving each functional module are filtered through feedthrough filters or filter networks. The filter network consists of an onboard common-mode choke and filter capacitors.

6. The electromagnetic protection method for live-line working robots based on three-level cooperative filtering and shielding according to claim 5, characterized in that, The robot is shielded using a pre-designed composite material casing, including: The robot's main body shell is made of a composite structure of conductive plastic and metal mesh, and a nickel-zinc ferrite conductive coating for shielding broadband electromagnetic interference is sprayed on the inner wall or outer surface of the shell in preset key parts.

7. The electromagnetic protection method for live-line working robots based on three-level cooperative filtering and shielding according to claim 6, characterized in that, System-level filtering and transient protection for all external cable ports includes: All external connectors passing through the robot's main body housing are filtered connectors, or a centralized filter protection plate is installed behind the external connectors; the filter protection plate integrates common-mode filters, transient suppression diodes, and gas discharge tubes for power, communication, and control lines; when the shielding layer of any external cable enters the robot's main body housing, a metal cable gland with electromagnetic compatibility is used.

8. The electromagnetic protection method for live-line working robots based on three-level cooperative filtering and shielding according to claim 7, characterized in that, Constructing an equipotential and grounding system includes: An equipotential bus is installed inside the robot's insulated bucket platform, and the grounding terminals of any metal shielding shell and filter in the robot are connected to the equipotential bus in a star topology.

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